eBay can timing tool

[Desmoben1]

Hi,
Couldn’t find a definitive answer to this. Before I waste more money....Does anybody rate these eBay renault cam locking tools that seem to be very cheap (£20-35)?
I mean how inaccurate can they be vs a well used genuine renault supplied item?

Thanks,

 

[R3k1355]

Pretty inaccurate.